Intent vs Actions

Basically my question is whether intent or actions determine the evilness. Most times I see rankings here, people use the things a character has done to rank the characters "evilness", but sometimes the character is either not using their abilities to their full extent, for example a drone pilot killing a dozen people then flying away despite being capable to shoot more, having no particular feeling’s towards his doing, while other characters are simply limited by their abilities , for example a serial killer who got caught on their fifth kill, but would, if given the same opportunity as the drone pilot, fire until the last shot, and then crash the drone into something to maximise the carnage, enjoying every moment of it.